传染性支气管炎病毒我国地方分离株病原性和基因分型的比较研究

PATHOGENICITY AND GENOTYPE OF INFECTIOUS BRONCHITIS VIRUS ISOLATES IN CHINA

对来自国内部分地区的６个分离株及３个参考株，以蛋白酶Ｋ－ＳＤＳ法提取其基因组ＲＮＡ，经反转录－聚合酶链式反应（ＲＴ－ＰＣＲ）扩增了预期的１．７ｋｂ纤突糖蛋白Ｓ１基因ｃＤＮＡ。用ＨａｅⅢ裂解Ｓ１基因ｃＤＮＡ，限制性酶切片段长度多态性（ＲＦＬＰ）表现为３种不同的带型。以部分毒株分别感染ＳＰＦ鸡，于感染后第５，９，１３，１６和２０ｄ观察气管和肾脏病理学变化，显示在病原性和组织嗜性上存在两大倾向。一类可导致严重的、持续时间较长的呼吸道损伤，伴有相对较轻的肾脏损伤；另一类以肾脏损伤较严重且持续时间较长而呼吸道损伤相对较温和为特征。结果表明我国部分地区同时存在着Ｍａｓ基因型的所谓“呼吸型”和Ｔ基因型或可能的变异株“肾病型”ＩＢＶ的流行，且后二者是引起“肾病型”ＩＢ广泛流行的主要病原。

The genome RNA of 6 IBV isolates from different regions in China and 3 reference strains of IBV were extracted by phone/chloroform following Proteinase K SDS digesting as templets.The 1.7kb cDNA fragments of S1 glycoprotein gene were amplified by reverse transciption poly merase chain reaction(RT PCR).The cDNAs of S1 gene were analyzed by restriction fragment length polymorphism(RFLP)with Hae Ⅲ and revealed 5 different patterns.When SPF chickens inoculated with above 6 IBV isolates,two predisposition of tissue tropism were found by histopathologic oberservation at 5、9、13、16、20 days post inoculation.One isolate caused more severe lesions with longer duration in the trachea and milder lesions in the kindey,while others characterized by more severe and longer renal lesions and mild tracheal lesions.These results indicated that the epidemic IBVs in China not only Mass but also of T genotype and putative variant strains.The epidemic of nephropathogenic IB in China may be mainly due to the T genotype and putative variant IBV strains.